Modeled after the Kievian Rus, the first Slavic kingdom of Norse origin, several principates had evolved eastern Europe being Novgorod the most important of them. After the invasion of the Mongols, the Muscovian principate was the first to break free from the Golden Horde and soon after begun a process of conquest, annexing Novgorod, Kiev, and many of the different Khanates.
Since then, Russia has been in constant struggle against the Khanates and successors in the south and east, and against Sweden and the Dual Commonwealth in the west, as well as the Ottoman Empire who mainly fought through allied or vassal Khanates. This constant struggle lead to the partition of Russia in late 18th century.
The Collapse of the Dual Commonwealth in 1916 lead to the re-establishment of Russia, comprising, however, a much smaller territory than the one they had in 1768: territories lost in late 18th Century to Sweden, Sibiria, Kazakhstan, Crimea and the Ottomans were lost for ever.
The New Russian Czardom attempted to gain some of the lost territories. In 1918, soon after the Frankfurt Treaty finally defined the final borders after the Great War of 1912, Russia invaded the newly created nation of Ruthenia. Annexation of Ruthenia was not an issue, however several territories were transferred from Ruthenia to Russia.
The next target was Novgorod, who was invaded in 1919 triggering the response of the whole Swedish Commonwealth. Soon Russia was defeated, but the status of the defeat was not defined, as the Swedish Commonwealth was a defensive treaty which forbade them to overthrown the Russian government. Finally the Czar recognized the defeat and the Duma recognized the independence of Novgorod.
Just after this defeat, the Czar abdicated, and the Duma opted for establishing a Republic. Further Russian ambitions were truncated, however problems with ethnic minorities and border adjustment lead to yet two other wars against Ruthenia (1923, 1956) and Crimea (1943).